KOL Insight: HR‑Positive/HER2‑Negative Breast Cancer (June 1, 2026)

KOLs emphasize the pivotal role of CDK4/6 inhibitors in HR+/HER2- breast cancer, especially in early‑high‑risk and advanced disease.

MONARCH‑E and M‑FAST data support adjuvant abemaciclib for high‑risk early HR+/HER2- disease, with sustained benefit beyond 2 years.

For metastatic HR+/HER2- disease, KOLs see no practice‑changing benefit of sequencing CDK4/6 inhibitors in later lines after prior exposure (SONIA trial).

Second‑line post‑CDK4/6 remains highly heterogeneous; KOLs favor oral SERDs (e.g., elacestrant) in ESR1‑mutated tumors and combinations such as capivasertib plus fulvestrant in PIK3CA/AKT‑pathway‑altered disease.

Next‑generation endocrine therapies and vaccine‑type platforms are emerging but still investigative; KOLs underscore the importance of biomarker‑driven strategies and clinical trial enrollment.